Determine your brain sex. This is an interesting test to observe. One of their questions went like this:

"You are given $50, and you must decide how much to keep for yourself and how much to give to your partner. Your partner then decides whether to accept the deal. If he rejects it, you both walk away with nothing. How much do you give him?"

The test seemed to be about testing your generosity threshold, but it’s actually a test about rationality, which the questioners apparently didn’t pick up on, silly social scientists that they are. If you are the player who has to accept or reject the deal, then they expect you to reject it if you get less than $25. This is rubbish. According to the rules given above, you should always accept the deal, even if you only get $1, because the alternative is that you get nothing!

If both players are rational, then the divider should offer the smallest amount possible, and the decider should accept that. Where the test becomes interesting is when the two players do not behave rationally. Unfortunately, game theory tells us nothing about this situtation, which is why we invoke psychology: perhaps it’s best to offer $25, since any less and your partner will reject just to spite you.

And despite my hyperrationalising, I still only have a borderline male brain…